The present invention relates to material finishing lines and more particularly to material finishing lines having a substantially linear array of work stations located in a building with constricted headroom. Most particularly the present invention is directed to material finishing lines where the work stations are liquid filled tanks into which the workpieces are successively dipped. Exemplars of such material finishing lines abound in the plating industry.
Frequently, with considerable expense, a plating operator will design its own line. In such circumstances, the typical design will include an overhead beam from which depends a traveling chain or cable hoist and from which a workpiece hook depends. The result while somewhat inexpensive can have a number of drawbacks. The principal drawback is the resulting dead space which shortens the lift range between the tops of the tanks and the workpiece hook for a given height of the beam. Where headroom for the material finishing line is limited, structural alterations to the floor or ceiling of the room may be necessary. A number of suppliers of plating lines usually avoid the extreme excessive dead space resulting from unsophisticated designers.
Examples of such lines are provided by U.S. Pat. No. 4,377,986 to Juve and U.S. Pat. Ser. No. 493,671, filed May 11, 1983 on behalf of Juve, each owned by McGraw-Edison Company, assignee of the present application. Each reduces the dead space over the unsophisticated design but neither a directed to providing minimal dead space in a comparatively low cost finishing line.
The patent titled "Hoist Plating Line" employs a vertically movable track along which a plurality of carts are horizontally propelled. While quite suitable in attaining its design goals, the hoist plating line does not minimize the dead space since the carts depend from the track and are in a vertically fixed relationship with the track.
Similarly the Patent Application titled "Hoist-Type Material Finishing Line" is quite suitable in achieving its objectives but does not provide a relatively low cost line with minimal dead space. There a self propelled hoist carrying a pick up arm slidably disposed on, and cantilevered from, a vertically extending guide transverses the line along a floor mounted track. The pick up arm has a substantial vertical extension since it is cantilevered and the floor mounting of the self propelled hoist may require floor leveling.